Loosen a "crusty" brake line fitting

[Hall]

Our son bought stainless steel brake lines for his car that he and I replaced earlier this week. Well, we replaced (3) of the (4). All of them seemed to have some dirt build-up in the fitting but we got three of them cracked loose and everything replaced fine. Using a flare wrench too, by the way. After cracking them loose, while unthreading them, you can literally hear the dirt in the fitting being broken up as you turn so I suspect the one we can't get just has more dirt than the others and is "jammed". Out of fear of rounding off the fitting, we left it as-is for now. The other (3) corners went surprisingly well otherwise. Replaced the fluid with Pentosin LV at the same time too.

We did spray it with brake clean before starting each corner to try and get rid of dirt. Penetrating spray didn't help on this one either.

Any ideas or suggestions ? Worst case, he'd have to have a shop try and break it loose or even cut it off, add a new fitting and flare the line.

Thanks !

 

[KGMtech]

Heat with a torch, provided this can be done without dangerous results.

 

[mk378]

This is an old line you're trying to remove? In that case cut the tube off at the nut then unscrew with a 6 point socket.

 

[Hall]

Originally Posted by mk378
This is an old line you're trying to remove? In that case cut the tube off at the nut then unscrew with a 6 point socket.

The 'hard' line comes into the wheel well and ends in a male flare fitting. That male fitting goes into the female fitting on the 'flexible' line that connects to the caliper. The connection / joint is at a bracket, secured by a flexible, steel clip.

This is a similar example: https://pitstopusa.com/files/TechTips/BRAKE%20LINE%20HOOKUP%20REFERENCE.gif. The fitting that we're having trouble with is the brass, male fitting on the right side (rigid brake line side). Here's another example: https://azoffroading.com/images/Jeep_JK_Extended_Brake_Lines_025.jpg. In this example, it would be the 12mm hex fitting.

 

[mk378]

The flare nuts are steel but they may be plated with a yellow material that looks like brass.

If the flare nut is rusted to the steel brake line you'll likely have to replace it (or redo the flare if there is enough extra length). You could try unscrewing by detaching the clip and pulling the fitting for the flexible line out of the bracket, then rotate the flexible line end so that the nut doesn't have to turn relative to the steel line.

 

[SubieRubyRoo]

AeroKroil, as long as the fluid can sit on/in the threads, will loosen just about anything. The catch is where the threads are vertically above where you can spray, meaning gravity can't help work the fluid into the threads. You can try heat like mentioned above, or if you know it's already buggered but have room to get in there, try to use a set of vicegrips with coarse jaws, and crank it down as tight as you possibly can to break it loose.

Or, take it to a shop for just that one line, and let it be their problem.

 

[CCI]

Safety note -- if you have used spray brake cleaner on these fittings be very careful with heat and make sure you do not breathe the fumes.

You might be able to use a heat gun safely if you are careful (I wouldn't) but if you use a torch and you heat brake cleaner residue past 300 degrees you can get a poisonous result. Some welders who prepped their work with brake cleaner have learned this the hard way, unfortunately for some it was their last lesson.

 

[FT92]

Originally Posted by KGMtech
Heat with a torch, provided this can be done without dangerous results.

I agree . just be safe

 

[Kawiguy454]

Squirt on some liquid wrench and let it sit for a day then repeat couple times. The "Dirt" is corrosion and it will suck/wick up the fluid and it will break loose much easier without using heat. Use a 6 point line wrench.

 

[Dave9]

At first I thought you meant you bought stainless hard lines, but now it seems you are putting more expensive stainless braided soft lines on but trying to reuse rusty hard lines.

This is not a good idea. We'd need a picture of the hard line to be sure, but if the nut is that rusted on, odds are that even with some slack to work with, it will be a problem trying to flare the existing line and get any reasonable service life out of it. So if it's not salvageable, there is nothing to lose by cutting the line and using a 6 pt socket to get the nut off, or not even trying to get the nut off if you're replacing the mating piece anyway.

If it is just rusted because of splatter from the wheel, you might be able to graft a new piece of brake line on with a flared union (not compression fitting), but otherwise the conservative choice is replace the entire hard line. Since you are in Ohio and I'm familiar with their winters and salted roads, I recommend using CuNi replacement line due to being corrosion resistant and easy to work with, bending and flaring.

 

[eljefino]

Originally Posted by Dave9
At first I thought you meant you bought stainless hard lines, but now it seems you are putting more expensive stainless braided soft lines on but trying to reuse rusty hard lines.

This is not a good idea. We'd need a picture of the hard line to be sure, but if the nut is that rusted on, odds are that even with some slack to work with, it will be a problem trying to flare the existing line and get any reasonable service life out of it. So if it's not salvageable, there is nothing to lose by cutting the line and using a 6 pt socket to get the nut off, or not even trying to get the nut off if you're replacing the mating piece anyway.

If it is just rusted because of splatter from the wheel, you might be able to graft a new piece of brake line on with a flared union (not compression fitting), but otherwise the conservative choice is replace the entire hard line. Since you are in Ohio and I'm familiar with their winters and salted roads, I recommend using CuNi replacement line due to being corrosion resistant and easy to work with, bending and flaring.


+2, all this.

 

[buck91]

Spray every day with a good penetrant like Kroil or 50/50 acteone and ATF. Do this for 1-2 weeks. Before trying to loosen it again wire brush off the exposed threads. Use a quality flare wrench. Be patient. Try alternating tightening and loosening. Try tapping the wrench with a hammer- for a long time.

Finally, be prepared to shear the brake line. They are fairly easy to splice sections of new hard line in with a cheap flare tool. The Nicop line is super easy to work with and much less susceptible to corrosion.

 

[Hall]

Originally Posted by Kawiguy454
Squirt on some liquid wrench and let it sit for a day then repeat couple times. The "Dirt" is corrosion and it will suck/wick up the fluid and it will break loose much easier without using heat. Use a 6 point line wrench.

Originally Posted by buck91
Spray every day with a good penetrant like Kroil or 50/50 acteone and ATF. Do this for 1-2 weeks. Before trying to loosen it again wire brush off the exposed threads. Use a quality flare wrench. Be patient. Try alternating tightening and loosening. Try tapping the wrench with a hammer- for a long time.

I've got Liquid Wrench and PB Blaster. I think my son used the Liquid Wrench on it. We let it sit while we worked on the opposite side and then tried it again after we finished. Didn't 'force' it so we left it alone. I can hit it with some spray a couple of times each day and we'll try again.

The threads aren't exposed to use a wire brush on though. I did try tightening (very gently) then loosening it and back and forth. I really won't push it too hard on this.

What do you mean with tapping the wrench with a hammer ? Do you mean tapping it to loosen it or tapping it to knock stuff looser ?

 

[Hall]

Originally Posted by mk378
You could try unscrewing by detaching the clip and pulling the fitting for the flexible line out of the bracket, then rotate the flexible line end so that the nut doesn't have to turn relative to the steel line.

I like this idea but I don't think it will work with the factory lines. They don't seem to have a hex fitting on them like the aftermarket braided lines do (17mm hex). We'll look though when we try and give it a 2nd go.

 

[vivaUkraine]

I've just gone through this on a 27 year old car. Flare nut wrench was of no use. It took me a few days of continuous application of penetrating oils (pb blaster, liquid wrench, Lucas), nice application of torch (use penting oil immediately after torch), then Erwin 5WR pliers. It will come off. Don't worry about rounding the fitting. You'll be able to tighten it with pliers.

So: torch -> immediately penetrating oil -> wait an hour -> Erwin 5WR